Interpretive Summary: Listeria monocytogenes is a potentially fatal pathogen that caused a major outbreak of foodborne listerisis associated with cantaloupe. This study was conducted to evaluate the effect of cold stress on the growth of this microorganism in fresh-cut cantaloupe and develop mathematical models to predict its growth. The results of this study can be used by the food industry to predict the growth of Listeria monocytogenes in fresh-cut cantaloupe during refrigerated storage.

Technical Abstract:
The aim of this study was to determine the growth kinetics of Listeria monocytogenes, with and without cold-adaption, on fresh-cut cantaloupe under different storage temperatures. Fresh-cut samples, spot inoculated with a four-strain cocktail of L. monocytogenes (about 3.2 log CFU/g), were exposed to constant storage temperatures held at 10, 15, 20, 25 or 30 deg. C. All growth curves of L. monocytogenes were fitted to the Baranyi, modified Gompertz, and Huang models. Regardless of conditions under which cells grew, the time needed to reach 5 log CFU/g decreased with the elevated storage temperature. Experimental results showed that there were no significant differences (P greater than 0.05) in the maximum growth rate k (log CFU/g per h) and lag phase duration L (h) between the cultures of L. monocytogenes with or without previous cold-adaption treatments. No distinct difference was observed in the growth pattern among three primary models at various storage temperatures. The growth curves of secondary modeling were fitted on an Arrhenius-type model for describing the relationship between k and temperature of the L. monocytogenes on fresh-cut cantaloupe from 10 to 30 deg. C. The root mean square error (RMSE) values of secondary models for non- and cold- adapted cells were 0.018, 0.021, and 0.024, and 0.039, 0.026 and 0.017 at the modified Gompertz, Baranyi, and Huang model, respectively, indicating that these three models presented the good statistical fit. This study may provide valuable information to predict the growth of L. monocytogenes on fresh-cut cantaloupes at different storage conditions.